Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$132.58	12.330%	$148.9271	$148.93	$148.95	$148.90
Purchase #2	$45.44	9.622%	$49.8122	$49.81	$49.80	$49.80
Purchase #3	$203.35	5.663%	$214.8657	$214.87	$214.85	$214.90
Purchase #4	$67.35	7.658%	$72.5077	$72.51	$72.50	$72.50
Purchase #5	$229.42	8.203%	$248.2393	$248.24	$248.25	$248.20
Purchase #6	$245.90	9.703%	$269.7597	$269.76	$269.75	$269.80
Purchase #7	$79.69	13.392%	$90.3621	$90.36	$90.35	$90.40
7 purchase totals =	$1,003.73		$1,094.4738	$1,094.48	$1,094.45	$1,094.50